For example, a paint spray gun which atomizes jetted paint by supplying air needs an appropriate control of a spraying air pressure. Because of this, as is disclosed, for example, in Japanese Unexamined Patent Publication No. 2003-211034, a paint spray gun is known in which a pressure sensor unit is fixed to a gun main body with a screw, which pressure sensor unit incorporates an air induction port which is connected to an air passage in the gun main body, a pressure sensor, and a display which displays a pressure value detected by the pressure sensor.